Abrasive and boring method using the same

Abstract

The present invention relates to an abrasive that decreases the heat generation by a core bit due to boring and allows the boring of a deep hole while maintaining the boring speed even when a deep hole is cut using a dry method. This abrasive contains abrasive grains, particles of anhydrous silica having a particle diameter from 5 nm to 50 nm and silanol groups in the surface thereof, and hydrous resin which discharges water when the hydrous resin is pressed by a core bit or the temperature of the hydrous resin rises. The abrasive 51 is supplied between the distal end of a rotating core bit 11 and a working material 20.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to an abrasive which can be advantageously used for dressing diamond segments of a core bit when boring a working material such as asphalt or concrete by the core bit, and a boring method using the abrasive.[0003]2. Description of the Related Art[0004]Conventionally, for boring a working material such as asphalt, concrete, or the like, a boring method is known in which a circular groove is cut into the working material wherein a core bit, which has diamond segments comprising diamond abrasive grains or the like attached to the distal end opening of a cylindrical core, is pressed against the working material while being rotated by a drive source such as a motor.[0005]The diamond segments are formed by dispersing diamond abrasive grains or the like in a binder phase made by sintering a binder material such as a metal bond. To maintain an advantageous boring condition, the new diamond abrasive...

AI Technical Summary

Benefits of technology

[0014]Because the fluidity of the abrasive according to the first aspect is high, even in the case of boring a deep hole, it becomes possible to supply sufficient abrasive grains to the diamond segments on the distal end of the core bit, the dressing of the diamond segments can be carried out efficiently, and the heat generated due to the boring by the core bit can be decreased by preventing loading of the diamond segments by the chips. In addition, due to the particles of anhydrous silica, the fluidity of the chips is similarly increased, and thus the chips do not get clogged at the distal end of the core bit and can be efficiently discharged, and the heat generation by the core bit can be reduced by decreasing the frictional heat between the chips and the working material. In this manner, the boring of a deep hole can be carried out using a dry method that reduces the heat generation by the core bit while maintaining the boring speed without a reduction.

[0031]In this case, due to the particles of anhydrous silica, the fluidity of the abrasive becomes high, and the abrasive can be sufficiently supplied to the diamond segments at the distal end of the core bit. In addition, the diamond segments can further be cooled by efficiently supplying a hydrous resin and a sublimate in the abrasive to the diamond segments. Thereby, the boring of a deep hole can be carried out by the dry method in which the heat generation by the boring of the core bit is decreased, and while maintaining the boring speed without a reduction, the boring of a deep hole can be carried out using a dry method.

Problems solved by technology

However, in the case that the working material is hard, because the chips are reduced to fine particles, not only is realizing the dressing function of the diamond segments impossible, but the chips adhere to the binder material, the diamond abrasive grains are surrounded, and a ceramic-like state is formed having a surface that is dense and smooth.

This is because in the case of boring a deep hole by the dry method, even if the cooling fluid such as compressed air can be delivered along with the abrasive to and the distal end of the core bit, it is blocked in the narrow gap between the inner circumferential surface of the core bit and the inner circumferential wall of the cut groove that is being cut, and thus sufficient compressed air and abrasives cannot be supplied up to the distal end of the diamond segments.

In particular, in the case of boring a deep hole by the dry method, there is the problem that the abrasives become obstructed before they arrive at the distal end of the core bit, and as a result, the diamond segments are not sufficiently dressed.

Between diamond abrasive grains of the diamond segments or the regions that extend towards the upper axial direction from the diamond segments, the part indicated by the slanted line in FIG. 5 (shown in the figure by R), loading occurs due to the chips, the boring speed decreases due to the core bit becoming heated, and in the case of boring a hard working material such as hard reinforced concrete, there is the problem that boring can only be carried out part way.

Therefore, when applying the dry method, in the case that the boring speed decreases, it is necessary to suspend the operation and extract and cool the core bit, or carry out the dressing of the diamond segments using a dressing, or replace the core bit, and these operations involve a considerable increase in labor and time.

However, in most cases, work is carried out while people inhabit the structures that are the object of the work, and thus there are many times that it is desirable to avoid using this wet method that employs water because the sludge into which the chips and the dust are mixed that occurs due to the drying of the sludge causes deterioration of a residential environment.

Thus, in order to prevent contamination of the surrounding environment, there is a strong demand to carry out the boring of deep holes using the dry method, while at the same time there is the problem that when using the dry method, presently the labor and time for the boring operation increases drastically.

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